Re: [PATCH 01/15] cxl/aer/pci: Add CXL PCIe port error handler callbacks in AER service driver

Dan Williams
2024-10-22T01:54:05Z

Terry Bowman wrote:
> CXL protocol errors are reported to the OS through PCIe correctable and
> uncorrectable internal errors. However, since CXL PCIe port devices
> are currently bound to the portdrv driver, there is no mechanism to
> notify the CXL driver, which is necessary for proper logging and
> handling.
>
> To address this, introduce CXL PCIe port error callbacks along with
> register/unregister and accessor functions. The callbacks will be
> invoked by the AER driver in the case protocol errors are reported by
> a CXL port device.
>
> The AER driver callbacks will be used in future patches implementing
> CXL PCIe port error handling.
>
> Signed-off-by: Terry Bowman <terry.bowman@amd.com>
> ---
> drivers/pci/pcie/aer.c | 22 ++++++++++++++++++++++
> include/linux/aer.h | 14 ++++++++++++++
> 2 files changed, 36 insertions(+)
>
> diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
> index 13b8586924ea..a9792b9576b4 100644
> --- a/drivers/pci/pcie/aer.c
> +++ b/drivers/pci/pcie/aer.c
> @@ -50,6 +50,8 @@ struct aer_rpc {
> DECLARE_KFIFO(aer_fifo, struct aer_err_source, AER_ERROR_SOURCES_MAX);
> };
>
> +static struct cxl_port_err_hndlrs cxl_port_hndlrs;

I think this can afford to splurge on a few more letters and make this

static struct cxl_port_error_handlers cxl_port_error_handlers;

> +
> /* AER stats for the device */
> struct aer_stats {
>
> @@ -1078,6 +1080,26 @@ static inline void cxl_rch_handle_error(struct pci_dev *dev,
> struct aer_err_info *info) { }
> #endif
>
> +void register_cxl_port_hndlrs(struct cxl_port_err_hndlrs *_cxl_port_hndlrs)
> +{
> + cxl_port_hndlrs.error_detected = _cxl_port_hndlrs->error_detected;
> + cxl_port_hndlrs.cor_error_detected = _cxl_port_hndlrs->cor_error_detected;
> +}
> +EXPORT_SYMBOL_NS_GPL(register_cxl_port_hndlrs, CXL);
> +
> +void unregister_cxl_port_hndlrs(void)
> +{
> + cxl_port_hndlrs.error_detected = NULL;
> + cxl_port_hndlrs.cor_error_detected = NULL;
> +}
> +EXPORT_SYMBOL_NS_GPL(unregister_cxl_port_hndlrs, CXL);
> +
> +struct cxl_port_err_hndlrs *find_cxl_port_hndlrs(void)
> +{
> + return &cxl_port_hndlrs;
> +}
> +EXPORT_SYMBOL_NS_GPL(find_cxl_port_hndlrs, CXL);

I guess I will need to go deeper into the code, but I would not have
expected that new registration interfaces are needed. Each 'struct
pci_driver' could optionally include CXL error handlers alongside their
PCIe error handlers and when CXL AER errors are broadcast only the CXL
handlers are invoked. I.e. the registration is something like:

diff --git a/drivers/pci/pcie/portdrv.c b/drivers/pci/pcie/portdrv.c
index 6af5e0425872..42db26195bda 100644
--- a/drivers/pci/pcie/portdrv.c
+++ b/drivers/pci/pcie/portdrv.c
@@ -793,6 +793,7 @@ static struct pci_driver pcie_portdriver = {
.shutdown = pcie_portdrv_shutdown,

.err_handler = &pcie_portdrv_err_handler,
+ .cxl_err_handler = &cxl_portdrv_err_handler,

.driver_managed_dma = true,